Eyeglasses can be made of specific colors for visual enhancement of certain colors under certain viewing circumstances. For example, yellow, orange and red lenses will block wavelengths of 400 nm. to 530 nm. range which constitute violet, blue, blue-green and green light. This elimination of the shorter wavelengths (400 nm. to 530 nm.) allows the longer wavelength light (530 nm. to 750 nm.) to be perceived better. Chromatic aberration is reduced and focusing is sharper.
Blue colored lenses will block the red-orange-yellow light spectrum having wavelengths in the range of (530 nm. to 750 nm.). The elimination of these longer wavelengths allows objects radiating shorter blue-cyan-green wavelengths of light (400 nm. to 530 nm.) to be perceived better. Elimination of red-orange-yellow wavelengths of light enhances both focusing of and perception in the blue, cyan and green spectrums having wavelengths of (400 nm. to 530 nm.). Lenses that block red-orange-yellow light enhance viewing in circumstances where blues predominate, such as in shadows.
Heretofore a viewer had to choose to wear, either yellow glasses that blocked the blue light, or blue glasses that blocked the yellow light.
In U.S. Pat. No. 3,877,797 to William Thorton, Jr., color discrimination was improved by eliminating two narrow, selected bands of light to better delineate color boundaries and increase subjective color perception. This was achieved by cementing yellow and blue filters together into a single lens. The lenses could be used in spectacles.
Thorton's invention does not enhance color vision. It only allows one to better distinguish color boundaries such as when green becomes yellow, or red becomes orange. It does nothing to augment perception in color-deficient individuals.
In U.S. Pat. No. 3,701,590 to Harry Zeltzer, color discrimination is enhanced by using a red contact lens in only one eye. This is based on subjective responses and the subjects' improved ability to see patterns in the Ishihara color testing plates. There is no explanation as to mechanism of achieving these results.
In U.K. Patent 1,141,252 to Kurt Esterson, protective goggles are used in which one eyepiece filter plate is yellow and the other eyepiece filter plate is orange. The purported purpose is to afford protection against dazzle and to increase the contrast of objects observed.
In U.S. Pat. No. 1,745,107 to Rafael Mendoza, lenses of different colors before each eye are used in a cinematographic device to achieve a visual effect of "a single image of each picture standing out in relief". Mendoza makes no reference to color integration or viewing in the natural environment, but only to color use in "stereoscopic views".